A copy-forgery-inhibited pattern image including added digital information is generated by an on-demand output of the pattern by a printer. An image processing apparatus for generating a copy-forgery-inhibited pattern image includes: a pattern storage section for storing a plurality of patterns that constitute a camouflage pattern image and that respectively represent specific bit values; an information input unit for inputting arbitrary information; and a camouflage pattern image structuring unit for receiving the information from the information input unit to represent a bit string of a binary representation of the information as an arrangement of a plurality of patterns. The image processing apparatus further includes a random number generation unit for generating a random number sequence; and a selection output unit for receiving the random number sequence from the unit and the information outputted from the information input unit to output, based on predetermined information, any one of them.